2011年盈江5.8级地震前近场流体异常初探*

(1.云南省地震局,云南 昆明 650224; 2.腾冲县防震减灾局,云南 腾冲 679100)

盈江5.8级地震; 前兆观测; 宏观异常; 短临异常

Preliminary Study on Fluid Anomaly in Near Field before Yingjiang MS5.8 Earthquake in 2011
LIU Xiang1,FU Hong1,WU Guo-hua1,ZHAO Xiao-Yan1,YANG Deng-bu2,MAO Yan1

(1. Earthquake Administration of Yunnan Province,Kunming 650224,Yunnan,China)(2. Earthquake Administration of Tengchong Country,Tengchong 679100,Yunnan,China)

Yingjiang MS5.8 earthquake; near field; fluid anomaly; discussion on the mechanisms

备注

通过对2011年3月10日盈江5.8级地震近场区水位、气汞等前兆观测资料的分析,发现该地震前震中附近区域的前兆观测异常较为显著,2010年初异常开始出现,7月后异常数量显著增加,盈江5.8级地震前1个月前兆异常出现转折、异常数量开始减少; 怒江断裂以西的震中附近地区异常以水位升高和气汞浓度增加为主,显示震区附近地区受到挤压,孔隙压力增加的应力状态; 短临阶段异常由外围向震中迁移的特征可作为地点预测的参考依据。最后对近场异常从机理上进行了初步的探讨。

Analyzing the precursory observation data of water level and gas mercury in near field before Yingjiang MS5.8 earthquake on Mar. 10,2011,we found that the precursory anomaly was obvious in the area within 200 km range from the epicenter. The precursory anomaly appeared in early 2010,and the number of precursory anomaly items increased from Jul.,2010,however it decreased and the precursory anomaly appeared turning in one month before Yingjiang MS5.8 earthquake. The rising of water level and increasing of gas mercury concentration were the main precursory anomaly in the area near the epicenter in the west of Nujiang Fault,which showed that the area near the epicenter in extrusion leaded to the stress state of increasing of pore pressure. The characteristic of the short-term and impending anomalies was the migration from the periphery to the epicenter,which could be taken as the reference of epicenter location prediction. Finally,the mechanism of the near-field anomalies was preliminary discussed.